rockchip: add defconfig for firefly-rk3399

The file is from evb-rk3399_defconfig with changes:
- use rk3399-firefly dtb
- re-order by make savedefconfig

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
1 file changed